The conventional method of preparing titanate particles suffers from two significant drawbacks. First, grinding the dried solids must be done carefully so as to minimize formation of unusable fines. Second, since a wide range of particle sizes results from grinding, the particulate must be sized through sieves. These operations are time-consuming and inevitably cause loss of product. Sized titanates can then be loaded into columns in order to remove metals from radioactive waste solutions.
Spray-drying of solid materials is a method known in the art for preparation of useful solids, including titanates, pigments, and food stuffs. See, for example, Kirk-Othmer Encyclopedia of Chemical Technology, 4th Ed., John Wiley & Sons, New York, 1993; Vol. 8, p. 475-519, particularly pp. 505-508; C. Strumillo and T. Kudra, "Drying: Principles, Applications and Design," Gordon and Breach, New York, 1986, pp. 352-359; and Masters, K., Spray Drying Handbook, 4.sup.th Ed., John Wiley & Sons, New York, 1985; pp. 548-567, particularly pp. 549, 550 and 565.
Crystalline sodium nonatitanate has been disclosed as an ion exchanger for strontium in WO 97/14652. Certain binders are stated to be useful for binding the sodium nonatitanate into larger particles. Spray-drying is not disclosed.
In U.S. Pat. Nos. 4,138,336 and 5,128,291 spray-drying of porous titania in the presence of an inorganic binder is disclosed. Crystalline silicotitanates as ion exchangers have been disclosed in WO94/19277 and in Pacific Northwest National Laboratories publication PNL-8847, UC-510 (October 1993).